Fuel feed control for oil burners



Nov. 14, 1950 H. B. HoLTHousE FUEL FEED. CONTROL FOR OIL BURNERS Filed Feb. 28, 1946 Patented Nov. 14, 1950 FUEL FEED CONTROL FOR OIL BURNERS Harry vB. Holthouse, Chicago, Ill., assigner, by

mesne assignments, to

Vapor Heating Corpora.-

tion, a. corporation of Delaware Application February 28, 1946, Serial No. 659,826

2 (.llairnsn i This invention relates to improved means for controlling the delivery of liquid fuel and air into a combustion chamber.

A principal object of the invention is to provide a simplified proportioning device which will function to modulate the delivery of liquid fuel to a fire chamber in accurate proportions to the delivery of combustion air thereto, whereby correct proportions of fuel and air for effecting complete combustion may be maintained for high and low llame by controlling the volume or pressure of combustion air delivered to said fire chamber.

A further and more specific object of the invention is to provide a simplified control means for proportionately varying the supply of liquid fuel to a burner in proportion to variations in the delivery of air to said burner.

According to the present invention, the combustion air is delivered to the burner under pressure from a suitable source, and this pressure is utilized to increase the now of liquid fuel through a delivery orifice of a supply chamber to the burner and to simultaneously vary the effective area of the fuel delivery orifice in proportion to changes in the said air pressure and thereby maintain a uniform mixture of fuel and air for high and low flame operation of the burner.

It is, therefore, a specific object of the invention to provide an improved control apparatus of simplified construction which will function in the manner hereinabove described to proportionately vary the supply of liquid fuel to a burner in proportion to variations in the pressure of the combustion air delivered to the burner.

One approved form of apparatus for attaining the objects of the invention is illustrated in the accompanying drawing wherein:

The said source of combustion air under pressure is a blower I which is preferably operated by a variable speed electric motor II so that the volume and pressure of the combustion air may be varied by varying the operating speed of the motor.

The burner is shown diagrammatically as composed of a shell I2 provided with a partition I3 which divides the shell into a fire chamber I4 and an air receiving chamber I5. The air receiving chamber is connected to the blower I0 by means defining an air passage I6 leading from the blower ID to the air receiving chamber I5. It will be seen, therefore, that by varying the speed of operation of the motor II, the volume of combustion air delivered to the burner can be varied.

The liquid fuel may be conditioned for combustion, either atomized or vaporized, by any suitable means, since the fuel conditioning means per se does not constitute a part of the present invention, the present invention being confined to the means for controlling the delivery of fuel and air so as to maintain a desired mixture. For the purpose of convenience of illustration, the present invention is disclosed in connection with a means for conditioning the fuel for combustion, which is constructed and operates in accordance with the disclosure in United States Letters Patent 2,227,714 and 2,331,912. It will be sufficient, therefore, to describe the fuel conditioning and ignition system quite briey. The said means for conditioning the said fuel. as shown herein, comprises a cathode I 'I which is grounded to the shell I 2 and positioned in spaced relation to an anode I8. This element is formed with a fuel duct I8a therein for delivering the liquid fuel to a tapered nozzle end I8b where it is discharged at pressures slightly above atmospheric into the burner. The fuel is ignited by an electrostatic discharge which is maintained across the space between the cathode I1 and the anode I 8. A wire I 8c is connected to the said anode and leads to a suitable source of high frequency electric current. The end of the anode may be provided with a hood I8d which is positioned in the opening I3a of partition I3 and deects the combustion air outwardly along the conical face I 3b of said opening. The anode I8 is connected by means of a conduit i9 made of rubber or other electrical insulation with a conduit fitting 20, the latter of which is threaded into a passage 2l communicating with the interior of a fuel supply chamber 22. The passage 2i is restricted, preferably by means of a screw plug formed with a central orifice 23 therein, defining the maximum area of the fuel discharge opening leading from the fuel supply chamber into the fuel conduit i9. Liquid fuel is supplied to the chamber 22 from a supply pipe 24. A float 25 is hingedly supported at 26 to control a needle valve 2l for opening and closing the fuel supply port 28 so as to maintain a constant level of fuel in the chamber 22. The level of fuel is indicated by the reference character 29 and is a. substantial distance above the discharge orifice. Consequently, the fuel will flow by gravity through the orifice and into ie delivery conduit I9. The volume of this flow is preferably increased by subjecting the body of liquid fuel in the chamber 22 to the pressure of the combustion air in conduit I6. While the air pressure exerted on the body of liquid fuel will increase its ow through orifice 23, such increased ow will not be proportional to the increased pressure.

In order to maintain a flow of liquid fuel which will be proportional to the delivery of combustion air at different pressures, the invention, in addition to utilizing the pressure on the fuel body to accelerate its ,flow through the orifice 23, also provides means for automatically varying the effective area of the orifice 23 in response to variations in the air pressure so that the flow of fuel due to both the air pressure on the fuel and variations in the area of the discharge orifice will be proportional to the said air pressure.

The effective area of the fuel discharge orifice 23 1s controlled by a needle valve 30, the lower end 3i of which is tapered so that by raising or lowering the valve, the tapered end portion will proportionately increase or diminish the elective area of the orifice 23. The needle valve 30 is secured to a diaphragm 32 which is subject to the pressureof the combustion air as it passes from the blower to the burner. In order to provide a simplied construction for utilizing the air pressure to control the flow of fuel, the chamber 22 is preferably interposed in and forms a part of the conduit defining the air passage I6. The lower portion of said air passage extending through the chamber 22 is defined by the liquid level 29 and the upper limit of said air passage is defined by the flexible diaphragm 32. Any in; crease in the air pressure will increase the flow of fuel through the orifice 23 and simultaneously exert pressure upwardly against the diaphragm 32 to move the valve 30 upwardly and thereby increase the effective area of the ldischarge oriiice 23. The movement of the diaphragm 32 will be proportional to air pressure within the chamber 22 and consequently, the automatic adjustment of the area of the fuel discharge orifice 23 will result in varying the amount of fuel so that the amount delivered to the burner will be proportional to the volume of air delivered.

The diaphragm 32 is clamped in place between lateral flanges formed in the upper end of chamber 22 and a closure cap 33. The space 32 intervening between the diaphragm and the said cap is open to the atmosphere through a bleed port 35. This port may be adjusted by means of an adjusting screw 36. Preferably, a compression spring 31 surrounds the upper portion of the needle valve 30 and seats against the diaphragm 32. The other end of the spring seats against a head portion 38 of an adjusting screw. The corripression of the spring 31 may be adjusted by turning a nut 39 in an appropriate direction.

In order to prevent entrance of dust or other foreign matter into the lower portion of the fuel.

supply chamber 22, a screen diaphragm 40 is extended across a chamber 22 between the liquid level 29 and the air passage from the blower. This screen also functions as a re screen to prevent ignition of fuel in chamber 22 in the event of back re.

While the several novel principles of the present invention are illustrated in connection with one specific form of apparatus, it is to be understood that the apparatus herein shown is merely for the purpose of illustration and not intended as a limitation of the invention except insofar as vthe specific structure is specified in ,the claims.

I claim:

1. In a` control apparatus for maintaining a uniform mixture of liquid fuel and air comprising means for supplying said air under pressure including a. variable speed blower and a conduit leading therefrom to a predetermined location, a liquid fuel supply chamber interposed in and forming a part of said air conduit, whereby the fuel in the chamber is subjected to the air pressure maintained in said conduit, a fuel delivery conduit leading from a delivery orifice in said chamber to said predetermined location, a diaphragm positioned across said chamber and delining a wall portion of said conduit so as to respond directly to variations in the air pressure, a valve for controlling the outlet orifice secured to said diaphragm and adapted to proportionately vary the effective area of the fuel delivery orifice in relation to variations of the air pressure, and means for damping both the valve opening and valve closing movements of the diaphragm comprising means defining an air chamber positioned above the .diaphragm'having a restricted opening to the atmosphere and a valve for varying the effective size of said restricted opening.

2. In a control apparatus for maintaining a uniform mixture of liquid fuel and air comprising means for supplying said air under pressure including a variable speed blower and a conduit leading therefrom to a predetermined location, a liquid fuel supply chamber interposed in and forming a part of said air conduit, whereby the fuel in the chamber is subjected to the air pressure maintained in said conduit, a fuel delivery conduit leading from a delivery orifice in said chamber to said predetermined location, a diaphragm positioned across said chamber and deiining a Wall portion of said conduit so as to respond directly to variations in the air pressure, a valve for controlling the outlet orifice secured to said diaphragm and adapted to proportionately vary the effective area of the fuel delivery orifice in relation to variations of the air pressure, and means for damping both the valve opening and valve closing movements of the diaphragm comprising means defining an air chamber positioned above the diaphragm having a restricted opening to the atmosphere, a valve for varying the effective size of said restricted opening, a compression spring positioned to bear on the upper face of the diaphragm and means for adjusting the compression of said spring.

HARRY B. HOLTHOUSE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name v Date 857,808 Jackson June 25, 1907 1,267,760 Good May 28, 1918 1,363,868 Hardwick Dec. 28, 1920 1,393,280 Good Oct. 11, 1921 1,583,238 Scudder May 4, 1926 1,656,109 Fegley Jan. 10, 1928 1,665,145 Peltz Apr. 3, 1928 1,733,792 Good Oct. 29, 1929 1,781,174 Greenfield Nov. 11, 1930 2,020,778 Gregg Nov. 12, 1935 2,314,288 Reed Mar. 16, 1943 2,367,038 Martin Jan. 9, 1945 FOREIGN PATENTS Number Country Date 808,165 France Nov. 6, 1936 

